// ── Central keyboard shortcut registry ──
//
// Every keyboard shortcut — bare keys, combos, context-specific — is
// registered here via registerShortcut(). A single document-level
// keydown listener dispatches to the matching handler. The registry
// also drives the auto-generated #shortcuts help screen so the UI
// and the code always agree on what's available.
//
// Shortcuts that live on specific DOM elements (editor textarea,
// search input, canvas overlay, dialog) stay element-scoped because
// they depend on local module state (autocomplete visibility, etc.).
// Only document-level shortcuts are centralized here.

const registry = [];

const OVERLAY_IDS = ['modal', 'detail', 'search', 'calendar', 'gallery',
    'settings-overlay', 'help', 'shortcuts', 'email-overlay', 'tasks',
    'dialog', 'ascii-canvas-overlay'];

function isOpen(id) {
    return document.getElementById(id)?.classList.contains('open');
}

function noOverlay() {
    return !OVERLAY_IDS.some(isOpen);
}

function bodyFocused() {
    return document.activeElement === document.body;
}

/**
 * Register a keyboard shortcut.
 *
 * @param {object} opts
 * @param {string}          opts.key       — e.key value to match (e.g. 'a', 'Enter', 'Escape', '?')
 * @param {boolean}        [opts.ctrl]     — require Ctrl/Cmd
 * @param {boolean}        [opts.shift]    — require Shift
 * @param {boolean}        [opts.alt]      — require Alt
 * @param {function}       [opts.match]    — custom predicate (e) => bool; overrides key/ctrl/shift/alt
 * @param {function}       [opts.guard]    — extra runtime check; shortcut only fires when guard() is truthy
 * @param {number}         [opts.priority] — higher = checked first (default 0)
 * @param {boolean}        [opts.stop]     — call e.stopPropagation() + e.stopImmediatePropagation()
 * @param {string}          opts.section   — help-screen section header
 * @param {string}          opts.label     — human description for the help screen
 * @param {string}         [opts.keys]     — display string for the help screen (e.g. '⌃ S'); auto-built if omitted
 * @param {boolean}        [opts.hidden]   — true to suppress from the help screen
 * @param {function}        opts.handler   — (e: KeyboardEvent) => void
 */
export function registerShortcut(opts) {
    registry.push({
        key:      opts.key ?? null,
        ctrl:     !!opts.ctrl,
        shift:    !!opts.shift,
        alt:      !!opts.alt,
        match:    opts.match ?? null,
        guard:    opts.guard ?? null,
        priority: opts.priority ?? 0,
        stop:     !!opts.stop,
        section:  opts.section ?? 'misc',
        label:    opts.label ?? '',
        keys:     opts.keys ?? null,
        hidden:   !!opts.hidden,
        handler:  opts.handler,
    });
    // Keep sorted by priority desc so the dispatch loop can short-circuit.
    registry.sort((a, b) => b.priority - a.priority);
}

/** Return the full registry for the auto-generated help screen. */
export function getShortcuts() {
    return registry.filter(s => !s.hidden);
}

/** Utility guards for use in shortcut definitions. */
export const guards = {
    board:   () => bodyFocused() && noOverlay(),
    editor:  () => isOpen('modal'),
    detail:  () => isOpen('detail'),
    search:  () => isOpen('search'),
    email:   () => isOpen('email-overlay'),
    canvas:  () => isOpen('ascii-canvas-overlay'),
    noOverlay,
    bodyFocused,
    isOpen,
};

// ── Dispatcher ──

function isEditableTarget() {
    const el = document.activeElement;
    if (!el) return false;
    const tag = el.tagName;
    if (tag === 'INPUT' || tag === 'TEXTAREA' || tag === 'SELECT') return true;
    if (el.isContentEditable) return true;
    return false;
}

document.addEventListener('keydown', (e) => {
    const inEditable = isEditableTarget();

    for (const s of registry) {
        // Key match
        let matched;
        if (s.match) {
            matched = s.match(e);
        } else {
            if (s.key !== e.key) continue;
            if (s.ctrl !== (e.ctrlKey || e.metaKey)) continue;
            if (s.shift !== e.shiftKey) continue;
            if (s.alt !== e.altKey) continue;
            matched = true;
        }
        if (!matched) continue;

        // Suppress non-modifier shortcuts when focus is in an editable field
        // (allow Escape and function keys like F1 through)
        if (inEditable && !s.ctrl && !s.alt && !s.match && e.key !== 'Escape' && !e.key.startsWith('F')) continue;

        // Guard
        if (s.guard && !s.guard()) continue;

        // Fire
        e.preventDefault();
        if (s.stop) {
            e.stopPropagation();
            e.stopImmediatePropagation();
        }
        s.handler(e);
        return;
    }
});

// ── Auto-generated help screen ──

/** Render the #shortcuts overlay content from the registry.
 *  Called once after all modules have registered their shortcuts
 *  (typically at the end of app.js boot). */
export function renderShortcutHelp() {
    const container = document.querySelector('#shortcuts .shortcut-help-content');
    if (!container) return;

    const visible = getShortcuts();
    // Group by section, preserve registration order within each section
    const sections = new Map();
    for (const s of visible) {
        if (!sections.has(s.section)) sections.set(s.section, []);
        sections.get(s.section).push(s);
    }

    // Build HTML — each section is a block with a header + table.
    let html = '';
    for (const [name, shortcuts] of sections) {
        html += `<section>
            <h3 class="font-pixel text-[10px] text-t-accent mb-2 uppercase tracking-wider">${esc(name)}</h3>
            <table class="shortcut-table"><tbody>`;
        for (const s of shortcuts) {
            const keysHtml = s.keys
                ? s.keys  // pre-formatted HTML (kbd tags etc.)
                : `<kbd>${esc(s.key || '?')}</kbd>`;
            html += `<tr><td>${keysHtml}</td><td>${esc(s.label)}</td></tr>`;
        }
        html += `</tbody></table></section>`;
    }
    container.innerHTML = html;
}

function esc(s) {
    return String(s ?? '').replace(/&/g, '&amp;').replace(/</g, '&lt;').replace(/>/g, '&gt;');
}